* Add bell button

Fix #4890

* Remove duplicate type from post-deployment migration

* Fix legacy class type mappings

* Improve query performance with better index

* Fix validation

* Remove redundant index from notifications

* Fix being able to follow oneself by moving to an account that was following the old one

* Add specs

* Add spec to catch MoveWorker issue with local followers following both accounts

* Fix move worker breaking when a local account follows both source and target accounts

* Fix migration from remote to local account not sending Undo Follow

* Fix show_reblogs not being preserved for moved account's followers

Don't put Move handler on cooldown if it didn't run. Skip unmerging
from timelines to save unnecessary work.